Platform-scale.



w. H. .DRAUGHQN PLATFORM SGALE. APPLICATION IILEDGHAY 7, 1912.

mama. n-18,1913.

INI/ENTOR UNITED STATES PATENT OFFICE.

WILLIAM DRAUGHON, OF NASHVILLE, TENNESSEE, ASSIGNOR OF ONE-TENTH- TO I L. H. MONTGOMERY, OF NASHVILLE, TENNESSEE.

PLATFORM-SCALE.

Specification of Letters Patent.

Application filed May 7, 1912. Serial No. 695,648.

To all whom it may concern Be it known that I, WILLIAM H. DRAUGHON, a citizen of the United States, and a resident of Nashville, in the county of Davidson and State of Tennessee, have invented a new and useful Improvement in Platform- Scales, of which the following is a full, clear, and exact description.

My invention relates to that class of platform scales having the platform supported above the weighing I lever.

The object of this invention is (1) to provide means for causing all parts 'of the platform to move vertically at the same velocity at any point of the are described by the weighing lever; and (2) to reduce wear and friction in the moving parts of said means. The means heretofore employed for the first mentioned purpose may be adjusted so as to accomplish the desired result while the weighing lever is occupying a certain position (a substantially horizontal position), but as the lever passes from this positionthe imperfections of the means heretofore used are such that, under certain conditions, a perfectly parallel movement of the platform is not maintained.

The exact nature of my invention will be understood from the following complete description and the accompanying drawings, in which the preferred form of the invention is disclosed.

Figure 1 is a sectional elevation showing one type of scale provided with my improvement; and Fig. 2 is an elevation, partially in section, showing another type of scale provided with my invention.

By referring to the drawings it will be seen that the scale shown in Fig. 1 is provided with a fulcrum bearing 5, which may be constructed of agate or steel. and in which is disposed the fulcrum 6, which is secured to the lever '7. At a short distance from the fulcrum 6 the lever T is provided with a second knife-edge 8. on which rests the agate or steel bearing 9. with which the supporting member is provided. On this I supporting member. and disposed to the left. i at 11 and the right side of the orifice at 18 i would be forced against the pin at 18 so there is a platform 11. and also secured to this supporting member 10 there is a guide arm 12, which is bent and has an upwardly 15 on the guide link 16. At the opposite end E of the guide link 16 is another agate or s1 eel I perfect parallelogram necessarily results in bearing 1'7, with which engages the knife Patented Feb. 18, 1913;

edge 18, which is supported by the frame 19.,

The knife-edges 6, 8, 14 and 18 should-be so disposed that a straight line drawn from the lower edge of (3 to the upper edge of 8 shall be parallel with and exactly equal to a straight line drawn from the edge of14 to the edge of 18. This forms a wellknown mechanical movement known as a parallel movement, which is found in all scales of,

this class. The fundamental principle of this movement is: All parts of the various members forming the connection between the points 8 and 14 will always move in parallel lines and at exactly the same velocity.

My invention relates to the manner of supporting the platform above the knifeedge 8, and to the character of the bearings used in the guide link 16. Heretofore, the guide links have always been provided with orifices at each end, which loosely fit the pins used in' the place of the knife-edges 14 and 18. It is necessary, with the old type of construction, to provide loose fits in these connections, because, if the pins should fit tightly in the orifices, the resulting friction would destroy the sensitiveness of the scale In the old construction, furthermore, the

platform is usually so disposed that its cen support at S, the pin at 1-1 would be forced so far to the right as the clearance in the orifices at 14 and 18 in the guide link would allow it t go. be moved-across to the left edge of the platform the pin at 14 would be forced against the left side of the orifice in the guide link that the pin at 11 would revolve around the pin at 18 in an arc of perceptibly shorter radius than before. It is impossible to have a perfectly adjusted parallelogram under both conditions.- and any variation from a Consequently. when But if the weight should '55. the loading or unloading the shifting the position ore, this arrangement permits of the lp the .lever for maintai-nlng-at all t1mes the a. variation of the indicated weight of a given load when placed in different positions on the platform because all parts of the platform would not be moving at the same velocity and consequently tlie load would be acting with different leverage atdifl'erent portions of the platform. a

In the type ofsc'ale shown in Fig. 2 of the drawings, the,lev'er-20 is provided with a o 'knife edgejmember 21, which -is fulcrumed onthe agate or steel bearing 22, the platform support 23 having an agate or steel bearing v 24, which rests on the knife edge member 25,

secured to the lever 20. This platform support '23 extends below the knife edge her 25, and. at its: lower end 23*. it is 'ded with a knife edge 26, disposed in W pro an opening 27 in the guide member 28 the knife edge 26 engaging a steelor agate bearing'surface 29. This'guide link 28 also has an opening 30, in which a knife-edge member 31 is disposed, the knife edge member 31 engaging an agate or-steel'bearing surface 32, on the guide link- 28. The kn'fe edge 35 member 31 is secured to the frame 8 in the usual manner. -Inthis construction, as the Y platform- 34 is secured to the support 33, and v extends to the right, it will tendataall t-ii'nesj to holdthe knife edge member 26 to the left, and in "engagement-with the steel or agate 'bearingsurface 29 on theguide link 28'. I?) .zthis way the knife ed e members 26 and 31 j will be held agaihst t e'bearing surfaces 29,. -"'and 32, without reference to the position in 35 which the weight should be disposed on the platform .34. In other respects,theconstruction shownin Fig. '2' corresponds with the- 1 construction shown in Fig. 1.

' Anjexamination of the drawings will show thatI have overcome the faultsinrior con-- s'tructions by so mounting the plat orm with reference to its point of support'onthe lever, "thatea weight placed t any position on it u will'always exert the s me kind of force on the link 16 ori28.- In other words, if the construction is suchas is shown in Fig. 1 the force exerted on the. link-will always be a force of compression. If the various mem-i v hers aredisppsed as s own in Fig. 2, the link will constantly sust ina force of tension. i Not only does this arrangementv maintain an -bsolute uniformity of the thepreti'cal length.

pf the link, but also prevents the constantpounding of the link connections incident to, of the platform'or of the load. 'Furthe'nh I use of knife-edge bearings in the link-connections, thereby further reducing wear and friction-0f the parts. j I

Having thus described my invention, I claim as new and desire to secure by Letters. Patent: 7 1 -1. In a. scale, the-combina' J a lever fulcrumed relativelyto the-frameyai ionj of a frame,-

guide arm pivotally mounted upon the lever, a guide link articulatedito the guide arm and to theframe,fand a platform supported armin such a manner that the weight of the platform or of a load in any po'sitiori'on the platform will transmit pressure through the guide arm to the guide link always-1n the same direction. v

2. Inascale; thecombinat-ion of .a lli'ame,

guide arm articulated' to the lever, a guide link articulated to the guide arm and to the frame, -a platform secured to the guide arm i'nsuch a manner that all parts of the platform are disposed on the-same side of the vertical plane of the axis'of oscillation-at the point where the guide-arm is articulated to the lever.

link articulated to the guide arm and to the frame by means of knife-edge members and hearings, and a platform supported on the manner that theweight of the platform or of a load in any position on the platform will always transmit pressure through the g'uidearnrtq the gl'iidelink in the same direction.

'4. n'a scale, relatively to the frame, a guide prm'mount ed: on the lever, in, latform secured to the guide arm and disp sed substantially-at one side ofthe point atwhich the guide arm mounted on the lever, "a guide link, and

necting the guide link with the guide arm and with the frame. i

5. In a scale, a frame, a leten '{fulcrumed relatively to the frame, a guide-"arm. mountthe'guide arm and to the frame, and a platwhich the guide arm is mounted on the lever'fo'r maintaining at all times apressure on the guide arm and in the same direction. '6. Inna scale, a -fra me,a lever; fulc'rumed relatively to the frame, a guide rm mounted on the lever, -,a 'guidelink kni-f -edge memi- .be'rs and' bearings for connecting the guide link with the guide arm, and with the frame, a platform secured to the 'guide arm and disposed substantially at one side of the oint at which the guide arm is mounted on pressure on the guide arm'and in the same direction. g 7 In a scale, alever having a power and a weight arm and fulcrumed" therebetween and relatively on one arm of a lever fulcr'um'ed relatively to the franle, a-

3. In a scale, thecombinationof aframe, a ever fulcrumed relatively to the frame, a 1 guide arm articulated to the lever, a guide lever and secured to the guide arm in such a' knife-edge members and bearingsfor'con ed on the lever, a guide .link articulated to.

form secured tothe guide arm and disposed. substantially at one side of the point atthe combination of a frame,

to the-frame, a' guide arm pivot-ally mountedon thelever and connected with the guide I a'frame, a lever fillcrumed lated-to the guide arm and to the frame, and

.a platform supported on the last-mentioned arm of the lever, and connected with the guide arm in such a'manner that the weight of the platform or a load in anyposition on i the platform, will transmit pressure through t-he'guide arm to the guidelink in the same direction.

8. In a scale, the combination of a frame, a lever having a power arm and a Weight arm, and fulcrumed therebetween and rela-- tively to the frame, a guide arm articulated to one arm of the lever, a guide link articulated to the said uide arm and to the frame by means of kni e-edge members, and bearings, and a platform supported on the last mentioned arm of the lever and secured to the guide arm in such a manner that the weight of the platform or of a load in any position on the plat-form will always transmit pressure through the guide arm to the guid'. link in the same direct-ion.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

WILLIAM H; DRAUGHON. Witnesses:

C. G. RING, D. O. RING. 

